Electric Arc Furnace Nitrogen Reduction via Inert Atmosphere
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Solution Overview
Problem
Existing electric arc furnaces face challenges in efficiently reducing nitrogen content in steel melts, which affects the toughness and susceptibility to stress corrosion cracking of the steel produced.
Innovation Solution
The electric arc furnace is configured with a data acquisition and evaluation unit to indirectly determine the nitrogen content in the melt, and it includes a conveyor system for adding carbon carriers like directly reduced iron to reduce nitrogen absorption during the melting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional electric arc furnaces are used for steel production, then energy consumption is reduced compared to blast furnaces, but nitrogen content in the melt increases which negatively affects steel quality
Solution Approach 1:
The patent applies inert atmosphere by introducing a covering layer of inert gas (such as argon or nitrogen) over the molten steel in the electric arc furnace. This inert atmosphere prevents atmospheric nitrogen from dissolving into the melt during the steelmaking process, thereby reducing nitrogen content while maintaining the energy efficiency benefits of electric arc furnace operation.
Solution Approach 2:
The patent uses an intermediary substance (such as a flux or slag layer) that acts as a barrier between the atmospheric nitrogen and the molten steel. This intermediary layer prevents direct contact and nitrogen absorption, allowing the furnace to operate efficiently while controlling nitrogen content in the final steel product.
2Reliability
If nitrogen content in the melt is reduced to improve steel quality, then toughness and resistance to stress corrosion cracking improve, but process complexity increases due to need for precise control
Solution Approach 1:
The patent implements feedback control by continuously monitoring nitrogen content in the melt using sensors and analytical instruments. The system provides real-time feedback to the control unit, which automatically adjusts process parameters (such as inert gas flow rate, electrode position, or addition of nitrogen-binding materials) to maintain nitrogen content within target specifications, thereby improving steel quality without requiring complex manual intervention.
Solution Approach 2:
The patent employs self-service mechanisms where the system automatically manages nitrogen control through pre-programmed sequences. The control unit autonomously regulates inert gas injection, monitors melt composition, and makes necessary adjustments without operator intervention, simplifying the overall process control while ensuring consistent steel quality.
3Measurement precision
If real-time determination of nitrogen content is implemented, then nitrogen levels can be controlled to less than 70 ppm, but equipment complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical sampling and laboratory analysis systems with modern analytical instruments such as optical emission spectrometers or gas chromatographs that can directly measure nitrogen content in the melt. These instruments use electromagnetic or chemical principles to provide rapid, precise nitrogen measurements without requiring manual sampling procedures, thereby achieving high measurement precision with reduced operational complexity.
Solution Approach 2:
The patent utilizes parameter changes by monitoring physical or chemical parameters (such as gas composition, temperature, or spectral characteristics) that correlate with nitrogen content in the melt. By measuring these surrogate parameters in real-time, the system can determine nitrogen levels accurately without requiring direct nitrogen measurement, thus reducing equipment complexity while maintaining measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for the simultaneous or near-simultaneous determination of nitrogen content, enabling real-time adjustments to reduce nitrogen levels in the melt to less than 70 ppm, thereby improving steel quality and reducing CO2 emissions.
Implementation Method 1
The electric arc furnace is charged with scrap, sponge iron (often referred to as DRI for 'direct reduced iron') and/or pig iron and the heat required for melting is provided by electrical energy and electric arcs.
Implementation Method 2
it includes a conveyor system for adding carbon carriers like directly reduced iron to reduce nitrogen absorption during the melting process
Data Source
AI summary
The invention relates to an electric arc furnace having a furnace vessel with at least one electrode and a voltage supply connected to the at least one electrode, wherein: the furnace vessel has a lower vessel for receiving a melt and a cover for placing onto the lower vessel; the lower vessel has a tapping channel; and the cover has a retaining means for fastening the at least one electrode; the electric arc furnace is designed to determine a nitrogen content in the melt; and/or the electric arc furnace is designed to reduce the nitrogen content in the melt to less than or equal to 55 ppm, preferably to less than or equal to 45 ppm and particularly preferably to less than or equal to 35 ppm. The invention further relates to an operating method and to a use of an electric arc furnace.